Treatment of some diseases, such as Parkinson's Disease, includes administration of a drug which is a large neutral amino acid (LNAA) and which must cross the blood-brain barrier to be effective. For example, L-dopa, alphamethyldopa (Aldomet) and 5-hydroxytryptophan, which are LNAA, can be administered in the treatment of Parkinson's Disease, hypertension or myoclonus. Patients who take such drugs may exhibit variability in their responses to them and may suffer adverse effects, such as L-Dopa induced dyskinesia, from them.
It would be useful to have a means by which an individual's response to such drugs can be controlled and the adverse effects reduced.